combatpigg

My Feedback: (3)

4000686798 [Isn't Mansons' number 4000686797?] Look at it on the bright side, now you have a good excuse to buy $2000 worth of home machinist equipment so you can rebush the crankcase and "turn" the crank.

grassroots

CP,

Your on to me now that you know about my brother.

Actually I just picked a number because all the good names were gone!

I have a mill/lathe combo, but rebushing a new engine doesn't please me.

combatpigg

My Feedback: (3)

4000686798, I had the same feeling after spending half a day trying to get RCU to approve my screen name requests.
There really is a super fine line between too tight and too loose....not being a machinist, I still need to learn how to rebush cases to salvage some engines.

microsprint9

Well got my .07 on the test bench today, used a heat gun before starting for the first time to help loosen it up, fired up quickly, got about 14700 on an old windsor 6x3 prop, engine seems to vibrate a bit, check the prop and tried to balance it, took too much time sanding so i got an APC 6x3, balanced it, bolted it on for the next two runs. The next 2 runs seemed better, it would hold 16000rpm at one click rich from max rpm, still think i need to try a 6x2 to get the RPM up. Overall engine starts great, idles very well, throttle response is great now just gotts get some more rev's out of her. Fuel was Omega 10%

combatpigg

My Feedback: (3)

A Cox SureStart with a sampler bottle of Crown Royal tied to it will weigh less, cost less and put out more power.

microsprint9

Well i guess i'll have to go right to the COX website and buy some then.

combatpigg

My Feedback: (3)

You'll also need a roll of tie wire and some of those sampler bottles of Crown Royal, too.

microsprint9

So what kind of RPM can i get out of one of those $6.99 .049's on an APC 6x3? and how much would it cost me to modify it a throttled version?

combatpigg

My Feedback: (3)

With a Surestart you never know what you'll get, out of 10 that I bought, about 4 were real good runners. If you want to make your own custom throttle, I think about $1000 worth of machine shop equipment should get you well on your way.

grassroots

After buying my GP .07 and being excited about this little engine, my disapointment came when I ran it on the test stand. Only 16,000-16,500 out the box with a 6x3 is nothing to write home about.

There is enough metal in this baby you would think it would at least turn up close to a Cox .09, or .10 size engine.

Even if you bought 10 sure starts the cost would only be $69.90, if you got 4 good runners that's about $17.50 an engine plus a lot of extra parts fool around with. Who needs a throttle?

If your looking for a throttled engine, as I understand the AP WASP will give about 16,000 with a 6x3 out of the box for far less weight then the GP .07

Can someone please confirm the out of the box performance of the AP WASP???

OzMo

My Feedback: (3)

Get the Sure Starts, send me the Crown Royal

ProBroJoe

Sure, outta the box, my AP .061 turns a APC 5.7x3 @ 18,500 RPM on 25% Sig Champion fuel, which is enough for unlimited vertical on my 12 oz SureShark....Check out the [link=http://www.rcuniverse.com/forum/m_5706288/tm.htm]"Got a SureShark to build?"[/link] thread, post #163, for a link to a video of my AP .061 in the SureShark. I know the AP has gotten a lot of bad press, but I must be one of the lucky ones as mine runs like a champ.

Yuu

micro... it won't cost much to build a throttle ring for the throttle on a SureStart. One way is to use 1/2" ID copper water pipe, cut 1/2" or so long to fit over the lower part of the cylinder, saw a vertical slot in it to adjust the size, add an 'arm' for the throttle wire. The turning of the sleeve and slot opens and closes the exhaust port area, and it acts like a throttle. Dickiebird wrote a thread on it. Another way is to get a thin, brass "T" from the auto parts house [$2] and make a 'trombone' slide to control the intake air... there's a thread here on that too. Do a search for throttle....

KidEpoxy

There is a nice HowTo CopperPipe Throttle Ring in the Reedy FAQ [link=http://www.rcuniverse.com/forum/m_3747940/mpage_2/key_/tm.htm#]Post#40[/link] by McLintock

jeffie8696

I have an .051 with a throttle ring. Wonder what it will turn compared to the .07 ?

Dan Vincent

I was wondering if the TT .07 might make an ideal engine for a short nose WW-1 or a radial engine scale model such as a Dehaviland Beaver because you usually end up adding nose weight anyway. These models do not require toothpick props and ultra-high RPM.

A lot of guys like a small, quiet and slow flying scale model for the local ball field or retention pond.

I'm curious about a dieselized version. Might be quiet enough to ditch the muffler if weight is a concern.

Think I'll add a TT .07 to my want list.

jeffie8696

OK so at what point do we consider the engine being able to turn a larger prop at lower RPM and still maintain the same thrust? For example, when the P-47 was first introduced it was considered to have a weak climb rate until the development of the "Paddle Blade" propeller that took advantage of the torque . So what about these members that have developed devices to measure the thrust , maybe we can get some pertinent info . Will an OK Cub that doesn't turn high rpms with a small prop still deliver high thrust with a larger prop at lower rpms?

KidEpoxy

Are we talking about Texaco-izing a TT .07 ?
Throw a bonus head gasket or two on & drop the nitro a bit to swing the big lumber.

Who has TT07 numbers for a MAS 8x3 / 8x4 with +2gaskets on 10% ?

Mr Cox

I haven't had mine runned in yet, it hand starts easy though with a rich setting and throttle at near idle. On mine the crankkase tends to rattle at intermediate revs, I hope this goes away with a leaner setting...
I like the idea of using large prop for small scale flying, why do you need to lower the comp?

Also has anyone tried to fit a turbo plug on it, to improve the high end?

misfitsailor

My Feedback: (6)

For some of us who are not trying to go fast or 3-D, high rpm numbers mean little. For sport flying, a 1/2A motor that starts easily, never quits and can run on the same medium nitro fuel as one's larger engines is good enough. Swinging a largish prop if needed is also a plus.

Having said that, I will say that my GP-07 is, so far, is the weakest small engine I have ever run. (and truly the hardest to start and sort out for the first runs.) Too bad, as it is a real looker. Maybe when it breaks in a bit...

jeffie8696

"I like the idea of using large prop for small scale flying, why do you need to lower the comp? "


Unless I am wrong, you need to lower the comp ratio because the larger prop is causing higher dynamic compression due to flywheel effect, the pressure is building higher faster and you want to eliminate preignition.
Or conversly the propeller being harder to turn over is causing faster pressure buildup at ignition causing detonation(not the same as preignition).
Can we do some thrust tests with different props at full and half throttle? Anything repeatable or is this not practical? I do not see my plane being operated at full throttle for the entire flight so full power numbers may or may not mean it is making good thrust at half throttle depending on a multitude of factors ie: Bore and Stroke , intake limitations, compression ratio , exhaust limitations just to name a few.
I just obtained a nice .61 and have been told that underpropping it for speed is not recomended and to place a slightly larger prop than specified in order to keep the revs low and use the torque instead.
I like the idea of a lazy prop dragging my plane around like a mule than a tiny prop buzzing like a bumble bee. Dunno just my opinion.[]
My experience comes from building racing automotive engines so I may be missing some hidden 2 stroke principals.[]

grassroots

My GP .07 manual states recomended prop sizes as 6 x 3 and 6 x 4, it might trun a larger prop I haven't tried doing that yet.

But if we are to compare engines to engines the GP is rated at .07 and turning a 6 x 3 at 15,500 is sad news when considering the AP Wasp is rated at .061 and can turn the same prop faster. Then factor in the weight difference and it's even worse.

I have a 7 x 4 that can be tried out on the GP .07 for rpm readings. I have no way of measuring thrust output and do not care to do so.

combatpigg

My Feedback: (3)

The world is divided into 2 basic kinds of people, those who like TT .074s and those who don't.

jeffie8696

If anyone would like to send me one so I can form an opinion...............

KidEpoxy

Instead of adding Head gaskets to lower the comp,
the TT07 uses a standard plug, right?
... can they add a plug gasket or 2 to lower comp instead, low nitro%,
for the texaco-ish style of big props like 7x4 / 8x4


<tee-hee, I still think its fun to call a 8x4 a 'big prop' >